EVALUASI KOEFISIEN REAKTIVITAS TEMPERATUR MODERATOR REAKTOR DAYA PWR 1000 MWe

ABSTRAK
EVALUASI KOEFISIEN REAKTIVITAS TEMPERATUR MODERATOR REAKTOR
DAYA PWR 1000 MWE. Peningkatan keselamatan pasif dan keselamatan melekat menjadi faktor
penting dalam keselamatan reaktor. Salah satu parameter keselamatan melekat di reaktor daya
adalah koefisien reaktivitas. Dikatakan memiliki keselamatan melekat jika reaktor memiliki
koefisien reaktivitas negatif. Makalah ini meyajikan evaluasi koefisien reaktivitas temperatur
moderator (KRTM) PWR kelas 1000 MWe, yaitu reaktor AP1000 yang didesain Westinghouse.
Tujuan penelitian ini adalah mengevaluasi KRTM reaktor AP1000 yang ada pada dokumen desain
dengan fokus kepada efek konsentrasi boron pada KRTM tanpa memperhitungkan perubahan
densitas air. Perhitungan KRTM telah dilakukan dengan memodelkan teras AP1000 dalam 3-
dimensi dengan program metode difusi neutron 3-dimensi, BATAN-3DIFF. Temperatur air yang
dievaluasi adalah 20o
C, 50o
C, 100o
C, 200o
C dan 300o
C untuk tiga konsentrasi boron, 0 ppm, 827
ppm dan 1574 ppm. Hasil perhitungan menunjukkan bahwa nilai KRTM reaktor AP1000 sangat
dipengaruhi oleh konsentrasi boron, semakin tinggi konsentrasi boron menyebabkan nilai KRTM
semakin menuju ke nilai nol (positif). Hasil perhitungan menunjukkan juga bahwa nilai KRTM
positif pada temperatur rendah (50o
C) pada konsentrasi boron sebesar 1875 ppm. Akan tetapi
kondisi ini tidak mungkin tercapai karena konsentrasi boron maksimum didesain 1574 ppm. Hasil
penelitian juga menunjukkan bahwa kestabilan reaktor AP1000 pada daya tinggi (nominal) sangat
dijamin karena KRTM bernilai negatif.
Katakunci: PWR, AP1000, koefisien reaktivitas temperatur moderator, metode difusi neutron,
Batan-3DIFF
ABSTRACT
EVALUATION OF MODERATOR TEMPERATURE COEFFICIENT OF REACTIVITY FOR
THE 1000 MWE PWR NUCLEAR PLANT. Passive and inherent safety improvement have become
important factors in reactor safety. One of the inherent safety parameters in the power reactors is
the coefficient of reactivity. It will be classified has an inherent safety if the reactor has a negative
reactivity coefficient. This paper describes the evaluation of the moderator temperature coefficient
of reactivity (MTC) of PWR with 1000 MWe (electric), the AP1000 reactor designed by
Westinghouse. The objective of this research to evaluate the designed MTC of AP1000 reactor with
a focus on the effect of boron concentration on the MTC without water density changes. The MTC
calculations have been carried out by modeling the AP1000 core in 3-dimension geometry model
with a neutron diffusion method code, BATAN-3DIFF. The evaluated water temperatures are 20o
C,
50o
C, 100o
C, 200o
C and 300o
C with three boron concentration levels, 0 ppm, 827 ppm and 1574
ppm. The calculation results showed that the value of the MTC of AP1000 reactor is strongly
influenced by the boron concentration, the higher boron concentration could cause the value of the
MTC to be 0 (positive). The calculation results also showed that MTC is positive in the low
temperature (50o
C) for the boron concentration of 1875 ppm. However this condition is
unattainable because the designed maximum boron concentration is 1574 ppm. This research also
showed that the stability of the AP1000 reactor at high power (or nominal power) is guaranteed
because the MTC is negative.
Keywords: PWR, AP1000, moderator temperature coefficient of reactivity, neutron diffusion method,
Batan-3DIFF